Storage devices currently utilize interrupts to process I/O requests received from user-mode applications. For example, after completing a requested I/O operation, a storage device generates an interrupt which is transmitted to its host computer. The operating system of the host computer receives the interrupt and dispatches it to a kernel-mode interrupt handler, which identifies the corresponding I/O request and completes the request by providing an appropriate response to the requesting application.
The proportion of I/O processing time attributable to the above process may be unacceptable in systems which use modern Solid-State Drives or other low-latency storage devices, particularly under intensive I/O workloads. These issues are exacerbated in a virtualized environment, where the interrupt generated by the storage device must be delivered to a physical CPU, to a Hypervisor layer, and then to a virtual CPU. Moreover, a low latency storage device may be capable of delivering its I/O interrupts to only a limited number of CPUs. Consequently, the CPUs which receive the I/O interrupts may become saturated before the storage device reaches its maximum throughput.
Systems are desired to process incoming I/O requests without using hardware interrupts and while providing reduced latency and increased throughput. Further, systems are desired which exhibit the above attributes while conserving CPU usage as compared to other systems.